Conversion of alternating current (AC) power to direct current (DC) power is well-known in the prior art. One class of AC to DC power converting circuits utilizes diodes to provide full-wave rectification. Usually, a filter circuit is coupled to the output of the rectifier to reduce the ripple of the rectified output.
Although various power supply circuits are well-known in the prior art, typically these circuits are designed to convert single or multiple phase transmission line AC voltages to DC voltages. In these instances, AC power lines, such as ordinary house current, are coupled as inputs to the power supply. Most devices which require a DC voltage to operate have power supply circuitry which are coupled to the AC lines.
This additional power requirement poses troublesome connection concerns when a device is coupled to operate with present day table-top personal computers by increasing the number of cables and power lines associated with the overall computer network. What is desired is to have the additional units or peripherals which can be coupled to existing terminations and derive necessary power from such connections. That is, if an add-on unit is capable of being driven by existing communication signals, such as data signals, then these units can operate by sourcing power from existing terminals of existing units and will not require additional plugs or power lines.